Virtually all homes in the United States and other developed countries include a system for providing heated water. Traditional hot water systems include a tank for storing and heating water.
These systems often include a large tank encased in insulation and positioned with a heating element. The tank also includes an external thermostat control valve for manipulating the temperature of the water in the tank. The heating element heats the stored water in the tank to the temperature set on the thermostat control valve. Once the water is heated to the desired temperature, the heating element stops heating the water. If the water temperature falls below the desired temperature, the heating element turns on again to heat the water. This cycle continues indefinitely so that hot water is always available.
These traditional water heating systems fail to take into account the changing demand for hot water in a normal household on an hourly basis throughout the day. For example, in the morning more hot water is needed for showers, breakfast preparation and cleanup, and other household chores. In the mid-morning through the afternoon, the demand for hot water decreases as household members go to work and to school. Then later in the afternoon, hot water demand increases again for dinner preparation and cleanup, evening bathing, and more household chores. This means that in a 24 hour cycle, a normal household may only require hot water for only a fraction of that time.
Frugal homeowners quickly realize that keeping water heated during time periods when there is little demand for hot water is wasteful and expensive. Indeed, the U.S. Department of Energy estimates that water heating accounts for 14%-25% of energy consumption in a typical household. Homeowners with gas powered water heaters may attempt to combat the expense of keeping water heated all day by utilizing the thermostat control valve that is accessible on all gas powered water heaters. In an attempt to save money, a homeowner may turn down the temperature of his gas powered water heater during the time intervals when he knows that hot water will not be required. But this method of saving energy and money is problematic. The homeowner may forget to turn the water temperature back up after the water in the tank has been left to cool all day or night with no hot water available for morning showers and cleanup. Typical gas powered water heaters take 40 minutes to an hour to heat a tank of water. This means that the homeowner may be left without hot water when the demand once again arises. Additionally, when adjusting the temperature control dial on a water heater, a homeowner may turn the heat setting too high or too low. If the water temperature is too hot, there is a risk of scalding when extremely hot water is dispensed through the house's plumbing. If the water temperature is too low, the homeowner may not be able to effectively and comfortably bathe or do other household chores.
Several patents and patent applications teach inventions for automatically controlling water heaters. U.S. Pat. No. 2,266,244 to Osterheld teaches a manually adjustable time delay that is installed on electric water heaters. The Osterheld time delay requires a temperature probe be inserted into the water tank of an electric water heater. The Osterheld invention causes a delay in the energization of the electric heater beyond the start of an off-peak period so that water is not heated when the demand for hot water is low. (Osterheld, Col. 2, Lines 1-8) The Osterheld invention is directed to controlling electrical current to a water heater and not gas. Additionally, Osterheld does not teach a time delay that requires no alterations to the existing water heater.
U.S. Publication No. 2007/0051819 to Isaacson teaches a water heater with programmable low temperature mode. This is an apparatus for gas heated water heaters and requires a temperature probe be installed into the water tank of the water heater to monitor the temperature of the water. The Isaacson water heater has a high temperature mode and a low temperature mode. In low temperature mode, the temperature of the water is kept in a certain range of temperatures. In the high temperature mode, the water is heated above the low temperature mode range of temperatures. Isaacson does not teach an energy saving switch that can be installed with minimal effort on an existing water heater.
U.S. Pat. No. 6,920,843 to Wilson teaches a programmable water heater that can be programmed to provide hot water at different times of day. The Wilson programmable timer is powered by a solenoid rather than by typical wall current. As with Isaacson, Wilson does not teach an energy saving switch that can be installed with minimal effort on an existing water heater.
U.S. Publication No. 2011/0062248 to Subramanian teaches a programmable water heater thermostat controller that attaches over the temperature control unit of an existing gas or electric water heater. The Subramanian thermostat controller can be programmed to turn the water heater on and off at different times of day. It controls the water heater temperature by clamping the water heater thermostat control between two rollers that work together to rotate the thermostat control in one direction or the other. This clamping action is problematic because over time, the rollers may slip on the thermostat control or fail to rotate the thermostat control at all as the thermostat control stiffens with age and wear. The Subramanian thermostat controller is also installed in such a way that the water heater owner cannot manually override the controller in order to manipulate the thermostat control freely.
In light of the prior art, there is a need for a process for heating water to a target temperature during a given time interval. There is also a need for an energy saving switch that that utilizes this process and can be mounted on an existing water heater and securely connected to the thermostat control valve of the water heater in such a way that there will be no rotational slipping. Additionally, a need exists for such a switch that can be manually overridden if needed while remaining mounted on a water heater with no additional modifications to the water heater.